Fetal hemoglobin is the main oxygen transport protein in the human fetus, and it has a higher affinity for oxygen than the adult form of hemoglobin. This phenomenon is illustrated in the curve above:
Both fetal and adult hemoglobin are quaternary proteins composed of four protein subunits. However, adult hemoglobin is composed of two α (alpha) and two β (beta) subunits, while fetal hemoglobin is composed of two α (alpha) subunits and two γ (gamma) subunits.
In humans, the gene that codes for the alpha subunit is on chromosome 16, and the genes for both the gamma subunit and the beta subunit are on different loci on chromosome 11. Fetal hemoglobin is replaced by adult hemoglobin by the time a newborn is about six months old. The best explanation for this is that
Fetal hemoglobin is the main oxygen transport protein in the human fetus, and it has a higher affinity for oxygen than the adult form of hemoglobin. This phenomenon is illustrated in the curve above:
Both fetal and adult hemoglobin are quaternary proteins composed of four protein subunits. However, adult hemoglobin is composed of two α (alpha) and two β (beta) subunits, while fetal hemoglobin is composed of two α (alpha) subunits and two γ (gamma) subunits.
In humans, the gene that codes for the alpha subunit is on chromosome 16, and the genes for both the gamma subunit and the beta subunit are on different loci on chromosome 11. Fetal hemoglobin is replaced by adult hemoglobin by the time a newborn is about six months old. The best explanation for this is that
The correct option is C Feedback mechanisms from the environment gradually silence the expression of γ (gamma) subunits of the hemoglobin protein, and activate the expression of the gene coding for the β (beta) subunits.
The fetal Hb has α and γ proteins. When the fetus is exposed to the external environment after parturition, the gene for β protein is activated while the one for γ protein is silenced or not transcribed. Both the genes for the proteins are present on different loci of the same chromosome.So, the correct answer is 'Feedback mechanisms from the environment gradually silence the expression ofγγ (gamma) subunits of the hemoglobin protein, and activate the expression of the gene coding for the ββ (beta) subunits'
The fetal Hb has α and γ proteins. When the fetus is exposed to the external environment after parturition, the gene for β protein is activated while the one for γ protein is silenced or not transcribed. Both the genes for the proteins are present on different loci of the same chromosome.
